Dental material mixing holder and cooler

ABSTRACT

A combination dental material mixing slab holder and cooler which includes a base plate having a pair of spaced, upwardly projecting ribs for receiving a mixing slab and a central well, a sealed container in said central well and a reusable heat sink means within said sealed container.

tlited ttes Drake Jan. '7, I975 [5 DENTAL MATERIAL MIXING HOLDER 2,187,387 1/1940 Tregg 62/430 AND CQOLER 2,203,591 6/l940 Brown 62/530 2,492,479 12/1949 Howard 32/39 Inventor: Daniel a 1969 Carolina 2,664,716 1/1954 Warmon ..-62/430 Ave, N.E., St. Petersburg, Fla. 33703 Przmary Exammer-W1ll1am J. Wye Filed! p 1973 Attorney, Agent, or Firm-Alexander and Speckman [2|] Appl. N0.: 400,414

[57] ABSTRACT [52} U.S. Cl 62/458, 32/39, 62/457,

. 62/437, 62/430 A combination dental material mixing slab holder and [51] llnt. Cl. FZSd 13/00 cooler which includes a base plate having a pair of [58] Field of Search 62/257, 458, 529, 530, spaced, upwardly projecting ribs for receiving a mix- 62/437, 430, 457, 333; 32/39 ing slab and a central well, a sealed container in said central well and a reusable heat sink means within said [56] References Cited sealed container.

UNITED STATES PATENTS 1,723,630 8/1929 P1411611 62/458 9 C m? 2 Drawmg figures DENTAL MATERIAL MIXING HOLDER AND COOLER BACKGROUND OF THE INVENTION This invention relates to dental material mixing means. More particularly, this invention relates to means for cooling dental materials during the preparation thereof.

In order to obtain optimum results, dental cements and filling materials must be kept relatively cool during preparation. This is particularly so when orthophosphoric dental cements are mixed because the ratio of powder to liquid in the cement mixture can be advantageously maximized at lower temperatures.

Cooling means for mixing slabs for dental materials are known. One type of cooled mixing slab is illustrated by US. Pat. No. 2,492,479 and US. Pat. No. 1,980,533 where cooling is effected by providing a liquid which can be readily evaporated from an absorbent surface. This type of cooling means for a mixing slab must be specially prepared or charged immediately before use and is cumbersome.

Another type of cooling means is illustrated in US. Pat. No. 3,230,723 and in US. Pat. No. 3,712,072 where cooling is achieved by thermoelectric effects. These devices are relatively complicated and expensive.

It is an object of the present invention to provide a simple, inexpensive dental material mixing slab holder and cooler which is easy to use, which can be chilled or refrigerated until ready for use, and which can be placed in use immediately upon removal from cold storage without further preparation.

It is a further object of this invention to provide a dental material mixing slab holder and cooler which is reusable.

Still other objects of the invention will readily present themselves to one skilled in the art upon reference to the ensuing specification, the drawing and the claims.

SUMMARY OF THE INVENTION The present invention contemplates a combination dental material mixing slab holder and cooler which comprises a base plate provided with a pair of spaced, upwardly projecting ribs for receiving a mixing slab and further provided with a central well between the ribs. A sealed container is present in the central well and contains a reusable heat sink means such as a liquid having a relatively high heat capacity, preferably a liquid capable of undergoing a phase change at a temperature below ambient.

BRIEF DESCRIPTION OF THE DRAWING In the drawing,

FIG. 1 is a plan view of a holder and cooler embodying the present invention and holding a glass mixing slab in place; and

FIG. 2 is a sectional elevation taken along line 2-2 in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 2, combination dental cement mixing slab holder and cooler 10 comprises base plate 11 having upwardly projecting ribs 12 and 13 which are spaced relative to each other in order to slidably receive mixing slab l4 therebetween. Mixing slab 14 can be made of glass, stainless steel or other materials having relatively good thermal conductivity. Well 15 in base plate 11 contains sealed container 16 which is contiguous with the underside of slab 1 1 and in heat transfer relationship therewith. Sealed container 16 can be removable or can be permanently fixed within well 15.

Reusable heat sink means 17 is contained within sealed container 16. Heat sink means 17 is is a stable liquid or solid material, having a relatively high latent or sensible heat capacity. Preferably the material has a latent heat capacity and undergoes a phase change at a temperature below'ambient, such as water, water ethanol solutions containing up to about 50 percent by volume ethanol, various brines and the like. Exemplary of the brines that can be utilized is an aqueous solution containing about 25 weight percent sodium chloride, an aqueous solution containing about 25 weight percent calcium chloride and the like. Liquid metals such as mercury or solid metals such as iron or stainless steel are also suitable.

Base plate 11 preferably is made of a material that is a relatively poor conductor of heat. Suitable materials are molded plastics such as acrylonitrilebutadienestyrene (ABS), phenolics, polyamides, polyethylene, rigid foamed polyurethane, and the like, wood and similar materials.

Container 16 is made from a material inert to the heat sink means contained therein and which preferably has relatively good heat conductivity, for example aluminum, stainless steel or the like.

The mixing slab holder and cooler of this invention is prepared for use by storing sealed container 16, separately or together with holder and cooler 10, in a cold environment such as a freezer or refrigerator, or by immersion in an inert refrigerant such as a halogenated hydrocarbon, I e.g., dichlorofluoromethane, methyl chloride, liquid nitrogen, carbon dioxide snow, or the like, for a sufficient period of time to lower the temperature of heat sink means 17 to the desired low level. For use, sealed container 16 is removed from cold storage, mixing slab 14 placed in a heat transfer relationship onto sealed container 16, and the mixing operation begun. Alternatively, a mixing slab can already be in place on holder 10 prior to cold storage, or holder 10 and a mixing slab can be chilled separately and then combined prior to use. During the mixing operation, heat sink means 17 absorbs heat from the dental cement or filling constituents placed on mixing slab 141 due to the temperature differential therebetween and thus effectively cools the ingredients. A substantial temperature differential continues to exist between the dental cement ingredients on one hand and the heat sink means 17 on the other because of the relatively large heat capacity of the latter. I

After the dental cement or filling has been suitably prepared, combination holder and cooler 10 is returned to cold storage until needed again for a subsequent mixing operation. In the alternative, the relatively warm sealed container16 can be replaced by an- TABLE 1' RELATIONSHIP BETWEEN ATTAINABLE DENTAL CEMENT POWDER-TOLIQUID RATIO AND MIXING TEMPERATURE Temperature. F. Powder-to-Liquid Ratio 45 2.20 50 2.00 55 I .80 60 1.62 65 l .4 l 70 1.20 75 l .00 80 .80

TABLE II RELATIONSHIP BETWEEN AVAILABLE MIXING-WORKING TIME AND TEMPERATURE FOR DENTAL CEMENT HAVING POWDER-TO-LIQUID RATIO OF ABOUT 2:l

Available Mixing Temperature, F. Time Min.

The foregoing data show that a relatively lower temperature is very desirable when working with high powder-to-liquid ratios in dental cement in order to provide adequate mixing and working time before hardening begins.

TABLE III RELATIONSHIP BETWEEN POWDER-TO-LIQUID RATIO IN DENTAL CEMENT MIX AND AMOUNT OF FREE ACID PRESENT Powder-to-Liquid Ratio Free Acid. wt.-7r

0.7 l0.3 0.8 9.5 0.9 8.8 1.0 8.0 1.1 7.1 1.2 6.6 l.3 6.0 L4 5.0 L5 4.2 1.6 3.6 1.7 2.9

While on some occasions a slight amount of free acid normally present in the dental cement is desirable in order to obtain some etching of the tooth, generally excessive amounts of free acid are to be avoided. Inasmuch as a lower mixing temperature provides a much greater latitude in the relative amount of powder that can be present in a dental cement mix, the desired free acid content in a given instance-can be easily obtained.

The foregoing discussion and the drawing are intended as illustrative and are not to be construed as limiting. Still other variations within the spirit and scope ofthis invention are possible and will readily present themselves to the skilled artisan.

I claim:

1. A combination dental material mixing slab holder and cooler which comprises:

a base plate of a material that is a poor heat conductor having a pair of spaced upwardly projecting ribs for receiving a mixing slab and a central well between said ribs;

a mixing slab having good thermal conductivity fitting within said base plate ribs;

a sealed container of a material that is a good heat conductor in said central well and adjacent said mixing slab; and

a reusable heat sink means within said sealed container.

2. The combination dental material mixing slab holder and cooler in accordance with claim 1, wherein said reusable heat sink is a liquid.

3. The combination dental material mixing slab holder and cooler in accordance with claim 1, wherein said reusable heat sink is a liquid capable of undergoing a phase change at a temperature below ambient.

4. The combination dental material mixing slab holder and cooler in accordance with claim 2 wherein said liquid is water.

5. The combination dental material mixing slab holder and cooler in accordance with claim 2 wherein said liquid is water containing ethanol in an amount up to about 50 percent by volume.

6. The combination dental material mixing slab holder and cooler in accordance with claim 2 wherein said liquid is brine.

7. The combination dental material mixing slab holder and cooler in accordance with claim 2 wherein said liquid is an aqueous solution containing about 25 percent by weight sodium chloride.

8. The combination dental material mixing slab holder and cooler in accordance with claim 2 wherein said liquid is an aqueous solution containing about 25 percent by weight calcium chloride.

9. The combination dental material mixing slab holder and cooler in accordance with claim 1, wherein said reusable heat sink is metal. 

1. A combination dental material mixing slab holder and cooler which comprises: a base plate of a material that is a poor heat conductor having a pair of spaced upwardly projecting ribs for receiving a mixing slab and a central well between said ribs; a mixing slab having good thermal conductivity fitting within said base plate ribs; a sealed container of a material that is a good heat conductor in said central well and adjacent said mixing slab; and a reusable heat sink means within said sealed container.
 2. The combination dental material mixing slab holder and cooler in accordance with claim 1, wherein said reusable heat sink is a liquid.
 3. The combination dental material mixing slab holder and cooler in accordance with claim 1, wherein said reusable heat sink is a liquid capable of undergoing a phase change at a temperature below ambient.
 4. The combination dental material mixing slab holder and cooler in accordance with claim 2 wherein said liquid is water.
 5. The combination dental material mixing slab holder and cooler in accordance with claim 2 wherein said liquid is water containing ethanol in an amount up to about 50 percent by volume.
 6. The combination dental material mixing slab holder and cooler in accordance with claim 2 wherein said liquid is brine.
 7. The combination dental material mixing slab holder and cooler in accordance with claim 2 wherein said liquid is an aqueous solution containing about 25 percent by weight sodium chloride.
 8. The combination dental material mixing slab holder and cooler in accordance with claim 2 wherein said liquid is an aqueous solution containing about 25 percent by weight calcium chloride.
 9. The combination dental material mixing slab holder and cooler in accordance with claim 1, wherein said reusable heat sink is metal. 